Packages and modules of the kind set forth comprising light emitting diodes (LEDs) are well known. They may be used in a multitude of applications, such as (general) illumination, backlighting for LCDs or signs, etc. Typically, such packages include an electrical circuit. This circuit, for instance, consists of an electrostatic discharge protection diode arranged anti-parallel relative to the LED for protection against static electricity or reversed voltage. Alternatively, the circuit consists of a second LED, similarly arranged anti-parallel to the first, allowing the package to be driven with f.i. an AC current. Possibly, the two LEDs emit light at different wavelengths, allowing colour mixing.
The prior art packages lack colour stability under typical operating conditions. Amongst others the physical processes operating in the LEDs cause the light emitted to be sensitive to the junction temperature. Many active and passive feedback/forward control schemes have been proposed, relying on temperature or light sensors, to ensure colour stability of the light emitted. Classically, such sensors have been arranged inside a light emitting module or luminary comprising the packages as light sources. This, however, results in a complex device producible against high assembly costs. Furthermore, as the sensors are assembled in the module exterior to the packages, they have a low selectivity towards the identity and the contribution of the individual packages. In addition, known packages are only able to detect faulty LEDs via electrical means, such as the measurement of a voltage drop over an LED, when applying >2 access pins. For instance, applying a string of four LEDs in series in a single package having only two access pins, it is not possible to determine a single faulty led in the string with such a voltage drop measurement.